Minimum Fluidization Velocity of a Three-Phase Conical Fluidized Bed in Comparison to a Cylindrical Fluidized Bed

Abstract

Hydrodynamic characteristics of a gas−liquid−solid conical fluidized bed were studied and compared with both liquid−solid conical beds and three-phase cylindrical fluidized beds. The effect of bubbles on particle mixing, pressure drop, and minimum fluidization velocity were discussed. Minimum fluidization velocities predicted by modified Ergun equation which accounts for the variation of the cross-sectional area with the bed height were found to be in good agreement with the liquid−solid conical fluidized bed data. The models of Song et al. [Can. J. Chem. Eng. 1989, 67, 265] and Zhang et al. [Power Tech. 1998, 100, 113; PhD. Thesis, 1996], derived originally for three-phase cylindrical fluidized beds, respectively, were modified for the prediction of Umf in a three-phase conical fluidized bed by accounting for the geometrical variation of the conical bed. It is found that the modified Song et al. model gave a better agreement than the modified Zhang et al. model in comparison with the current experimental data. However, the prediction of the modified Zhang et al. model is much improved when the parameter α, fractional gas holdup, was estimated using the equation from the Song et al. model.